The more details that emerge sounds like terrorism or mentally disturbed. Of course, some would argue that the two are interchangeable.

Sounds like the opposite to me, a fight that's escalated to a murder when a knife was pulled. Which doesn't surprise me due to how many people carry these days. There are multiple stabbings in London every day. Typically a terror based attack involves multiple victims or potential victims and some form of religious statement. None of that appears to have happened with this incident.

Possibly something as mundane as an argument over a seat that escalated way too far.

''It is understood the dad and his attacker had walked away from the teenager to another carriage as they had a bust up after boarding at London Road station.
Police are unsure what sparked the argument but believe it is likely to have been for something as trivial as “bumping into each other”.

Stunned witnesses on the 12.58pm departure from Guildford said the mayhem came after a "vicious fight" between the two men following a row.

Punches are said to have been thrown at first before the attacker plunged the blade into his victim during the bloodbath.''

Two people have been arrested after a man was stabbed to death on a train in front of his 14-year-old son.

DCI Sam Blackburn from British Transport Police said: "This is a fast moving investigation and I am pleased that overnight we were able to arrest a man following a huge amount of police enquiries.

"The investigation is moving with good progress and we are now confident to say that this is not believed to be a random assault. In the moments leading to the violent killing, both men appeared to be involved in an altercation lasting three minutes.

"Nothing justified the extraordinary violence that followed, and we are concentrating our efforts on the on-going investigation."